Tuesday, March 30, 1999 Published at 23:33 GMT 00:33 UKHealthCloned embryos 'could treat leukaemia'Cells can be cloned from an embryoHuman cloning could be used to grow life saving bone marrow for children with leukaemia within three years, a leading scientist has predicted.

Dame Anne McLaren, head of the Wellcome Institute of Cancer and Developmental Biology at Cambridge, predicted the technique, known as in-vitro cloning, could lead to scientists creating spare-part tissue from a patient's own DNA in the laboratory.

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The technique, yet to be given the go-ahead in Britain, involves talking cells from the patient and extracting the nucleus containing the DNA material from one of them.

The extracted nucleus is then transferred into an empty, unfertilised egg which has had its own nucleus removed.

Once the egg has started to divide to form an embryo, cells can be removed from it and grown in a laboratory.

At this stage, the cells, known as stem cells, can still theorectically develop into any of the tissues of the human body.

Scientists believe they will be able to stimulate the stem cells to become muscle, nerve, or organ tissue, which can then be re-planted into the patient.

Perfect match

If the stem cells were originally cloned from one of the patient's own cells the tissue they went on to form would be a perfect match with the other tissues of the body, and there would be no problems of rejection when the new tissue was re-planted into the host.

Speaking at a conference on cloning in London, Dame Anne said: "The first use of this technology will probably be to provide healthy bone marrow grafts for children with leukaemia.

"We might see this happen in America within two or three years."

She said that if successful, the technique could be extended to other patients suffering from rare disorders where currently bone marrow transplants offer the only hope of a cure.

In December a green light was given to British scientists wanting to pursue this kind of research.

Experts from two high-powered committees advised the Government to change the law to allow such cloning experiments to go ahead. Ministers have yet to give their decision.